Media devices, such as a set top box, are configured to receive media content events from a broadcasting system. Non-limiting examples of media content events include audio content, data content, books, industry data, movies, news programs, sporting events, serial comedies or dramas, and other program events that are communicated to a media device by a service provider over the broadcasting system. Non-limiting examples of broadcasting systems include satellite systems, cable or other wire-based systems, or over the air (OTA) broadcasting systems.
Media content events were traditionally encoded (i.e., moving pictures experts group (MPEG) standard) at a constant bit rate and transmitted over the broadcasting system to one or more media devices over a constant bit rate channel. For example, standard definition television (MPEG-2 compression) is often encoded at 3.5 megabits per second (Mbits/s). Therefore, the transport channel would need to have a constant throughput of at least 3.5 Mbits/s to transmit the television content.
It has become advantageous to encode media content events using a variable bit rate, because for certain types of media events, such as a television program, the amount of data that needs to be encoded varies over time. Variable bit rate media content streams are able to keep video quality constant, but vary the bit rate over time since the amount of data required between video frames fluctuates over time. For example, an inactive portion of the media content event requires less data than a portion where there is a large amount of action. Thus it would be inefficient to encode such content at a constant bit rate.
However because of this fluctuation, variable bit rate content can cause problems for the transmission of media content events. Such problems include limited throughput of a transport channel and/or under utilization of a transport channel or a component of a transport channel. Accordingly, there is a need to provide broadcast systems that can reliably and efficiently deliver variable bit rate media content events to media devices.